1. Field of the Invention
The present invention relates generally to an erecting optical imaging system for compact copying apparatus, and more particularly, to an image transmitter for a copying apparatus of a slit exposure scanning type wherein the original document and the image recording member are relatively movable in a scanning direction relative to the image transmitter. The image transmitter includes an array set of parallel offset rows of lens elements that provide an overlapping field angle in the scanning direction.
2. Description of the Prior Art
The field of copying apparatus, particularly in the smaller compact copiers for office applications, has become increasingly competitive with demands for both speed and reproduction clarity. Various forms of optical systems have been suggested and utilized in the copier field, including plurality of erecting lens systems arranged in a direction transverse to the scanning direction. The problems of providing the reproduction clarity required while removing vignetting, spherical aberration, and field curvature problems have frequently plagued the prior art attempts to provide a compact scanning copier apparatus. Various suggestions have existed in the patent literature for image transmitters, such as those disclosed in the U.S. Pat. No. RE28,162, U.S. Pat. Nos. 3,447,438, 3,580,675, 3,584,950, 3,584,952, 3,592,542, 3,655,284, and 4,168,900. Additionally, various foreign patent publications have also addressed these prior art problems, such as Japanese Patent Application that has been laid open for inspection No. 54-17029, and Japanese Patent Application No. 45-30787.
While these image transmitters have succeeded in reducing the distance between the original document and the image recording member to permit the production of a compact copying apparatus, there is still a demand in the prior art to provide an improved image transmitter, especially for the purpose of increasing the speed or effective f number of the imaging lens system, while maintaining acceptable image-forming optical performance and ease of manufacturing.